Open Circulation Facies in the Cenomanian of the Northeastern Margin of the Friuli Platform: the Iudrio Valley Case (NE Italy)

Abstract

The Early Middle Cenomanian margin sequence of Val ludrio, connected with the northeastem margin of the Friuli Platform shows intercalated layers with pelagic organisms: Calcisphaerulidae and planktonic forams, among which is Favwsella. These are interpreted as transgressive episodes recorded in a calbonate ramp sequence related to a tectonically subsiding margin. ln the Dinaric and Friuli Platforms two distinct Calcisphaerulidae and planktonic forams facies are distinguished for the Cenomanian. The first one, of early-middle Cenomanian age, which is also present in the ludrio sequence, developed in platform margin zones subjected to drawning. The second one, of late Cenomanian age, developed in more internal areas of the Dinaric and Friuli Platforms, and can be related to the transgressionassociated with the OAE 2 event.